Conformal coating process in PCB Assembly manufacturing
In PCBA fields , more and more boards need to be kept from humidity ,dusty and high reliable insulation. So let go ahead to more information of conformal coating.
What’s conformal coating?
Conformal coating is the process of spraying a dielectric material onto a device component to protect it from moisture, fungus, dust,corrosion, abrasion, and other environmental stresses. Common conformal coatings include silicone, acrylic, urethane, epoxy, and Parylene.Parylene is a unique polymer conformal coating that conforms to virtually any shape including crevices, points, sharp edges, and flat, exposed internal surfaces. Parylene is a higher level coating process. It used on high quality, reliable,precision requirement products,such as medical equipment.
Three normal way to do conformal coating process
Brush coating works by flow coating the material onto the board and is suitable for low volume application, finishing and repair. The finish tends to be inferior cosmetically and can be subject to many defects such as bubbles. The coating also tends to be thicker and unless skilled operators used the coating, highly subjective in quality. And in this way you can add some fluorescent material to your coating liquid and when you work under a fluorescent lamp you can easily to find out which area or space is not covered the coating.
Spray application coating can be completed with a spray aerosol or dedicated spray booth with spray gun and is suitable for low and medium volume processing. The quality of the surface finish can be superior to all other methods when a trained skilled operator completes?the process, as long as the circuit board is clean and the coating has no adhesion issues. The coating application may be limited due to 3D effects but masking requirements are more shield than barrier since the penetration is less effective. However, the lack of penetration can be an issue where coating is desired to penetrate under devices.
Conformal coating dipping
is a highly repeatable process and if the PCB is designed correctly can be the highest volume technique. Coating penetrates everywhere, including under devices, and therefore any masking must be perfect to prevent leakage. Therefore, many PCBs are completely unsuitable for dipping due to design. The issue of thin tip coverage where the material slumps around sharp edges can be a problem especially in a highly condensing atmosphere. This tip coverage effect can be eliminated by double dipping the PCB, using several thin layers of anatomist spraying to achieve good coverage without exceeding coating thickness recommendations or a combination of the two techniques.
Conformal Coating Curing & Drying
Different Methods of curing / drying are available depending on the conformal coating material.Solvent & Water based conformal Coatings For standard solvent based acrylics, air drying (film forming) is the normal process except where speed is essential. Then accelerated heat curing can be used, using batch or inline ovens /conveyors and using typical cure profiles such as which are designed for max efficient curing without damage to the coating.Water based conformal coatings can be treated in the same manner but with more care with the application of the heat due to the slower drying times.
Leadsintec Co .,Ltd who is one of OEM manufacturer can supply above three normal way conformal coating’s supplier in south of China(Shenzhen City, Guangdong Province). They provided low and medium volume quantity conformal coating service for around 6 years?in the factory. You can get touch with them at following information.